Rev Jaleb Manurung, born on July 1, 1919, was a Batak missionary from Sumatra, Indonesia. After graduating from a mission school at Sipoholung in 1939, he served at the local Methodist church for eight years. He got married on February 22, 1947.
Rev Manurung and his family came to Sarawak on July 17, 1948 and served in Kapit among the Ibans, travelling in long boats into the interior. The government had granted land at Panto to build a school for the people but the project was disrupted due to the Second World War but work resumed when Rev Manurung came. Meanwhile, Rev Burr Baughman, the missionary who came at the same time focused on spreading the gospel. Both missionaries picked up the Iban language very quickly and, like Rev Mamora, these two preached in Iban and spread the gospel in the longhouses using Iban.
Ten years before they came, in 1939, Rev Mamora and Rev Schmucker had worked among the Ibans and their work was affected by the war as well. So, Rev Manurung had to revisit the Ibans to re-establish goodwill with the longhouse people and to regain their trust and friendship.
Mamora and Schmucker had tried to encourage the Iban parents to send their children to school at Panto whenever they had gatherings at the longhouses. Their hard work bore fruit in December 1949. The first batch of students consisted of 29 Ibans including Koh anak Jubang (later Temenggong Koh), Sibat anak Buyong (later Penghulu Sibat), Jugah anak Barieng (later Tun Jugah) and Jinggut anak Atan (later Penghulu Jinggut). Twenty of them were baptised and officially joined the Methodist church.
In 1954, Rev Manurung was posted to the Bawang Assan longhouse and he set up the first Iban church. In 1955, his brother-in-law, Philemon Sirait, another Batak missionary, and his family came to do mission work with him at Bawang Assan mission field. In 1949, Manurung was ordained as elder and was appointed as the superintendent of the Upper Rejang,
Rev and Mrs Mamora, Rev and Mrs Manurung, as well as Rev and Mrs Philemon were three missionary families of the Batak ethnic group from the Indonesian Methodist church.